Big piston rings

Sep 14, 2008 10 Replies

I heard a very useful tip the other evening. Someone restoring a big engine was stuck for piston rings & skimmed up a brake disk, parting out at the appropriate diameter. Similarly, a brake drum might also be helpful.



What a good idea! Fine grain cast iron & annealed over a number of years by repeated cycles of heating & cooling and being allowed to rust from time to time...............



regards,



Kim Siddorn


But, most are ventilated now, at least the van ones are, and they are usually surface cracked from heat when we get rid of ours.

The BMW discs used to have the same problem as well, they would start to crack through the ventilation/drainage holes.

Looking through a big pile of truck discs at the scrapyard the other day, they were almost exactly the same, just bigger. What you'd need is a new older type non-ventilated disc perhaps, or a new drum, I'd be a bit cautious with anything old and used.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk

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Heavy right foot is usually the big problem with cracking and not planning ahead, so I'm told. :-))

Where's your halo ? :-))

Some of the problems we have had were caused by towing the trailer fully loaded, and insufficient braking on the trailer brakes.

Having said that, as most of our mileage is without the trailer (less than 2% of mileage is with the trailer) and was almost all on motorways, it is difficult to see why they should suffer from cracking at all.

It was less of a problem with the old asbestos/metal brake pads than with the newer high-friction pads.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk

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My halo is where I usually keep it, on a hook in the van ready for emergencies :-))

Martin P

Look for rear discs. They're less likely to be ventilated, they do less work and so don't get so hot. I won't comment on heavy right feet!

John

Backs are still ventilated on the vans.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk

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Is that a problem? Even vented disks are still plenty thick enough for making piston rings out of, unless it's some humongous scraper ring with multiple lands.

Actually, a ventilated disk is just what you need for a scraper ring!

regards,

Kim Siddorn

"Andy D>

Now that would be a fearsome engine!

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